Propeller



Aug. 3, 1937. M. GRABARSE PROPELLER Filed July 16, 1935 Patented Aug. 3,193 7 err Manfred Grabarse, Berlin-Hermsdorf, Germany,

assignor to Gustav Schwarz G. in. b. H., Berlin- Waidmannslust, Germany,a iimited company of Germany Application July 16, 1935, Serial No.31,643

. In Germany July 20, 1934 '2 Claims.

My invention relates to improvements in propellers, and moreparticularly in propellers for air craft. One of the objects of theimprovements is to provide a propeller, in which the blade or blades arerigidly fixed to the hub. Another object of the improvements is toprovide a propeller in which the sleeve or sleeves in which the blade orblades are fitted may be made comparatively short, and in whichtherefore the mass of the hub is reduced. With these objects in view myinvention consists in constructing the hub with a longitudinally slottedsleeve having the blade fitted therein and clamping the said sleeve bysuitable means such as screws on the blade, the slot of the sleeveextending from the outer end thereof inwardly and beyond the end of theportion of the blade engaged thereby so far that the sleeve is inclamping engagement with the whole portion of the blade engaged thereby.

For the purpose of explaining the invention several examples embodyingthe same have been shown in the accompanying drawing in which the samereference characters have been used in all the views to indicatecorresponding parts. In said drawing Fig. 1 is a sectional plan viewshowing the hub of the propeller, a part of the propeller shaft and theinner ends or roots of the blades,

Fig. 2 is an elevation of the propeller shown in Fig. 1,

Fig. 3 is a sectional elevation taken on the line 3-3 of Fig. 1,

Fig. 4 is a sectional plan view similar to the one illustrated in Fig. 1and showing a modification in which the length of the sleeve and theportions of the blades engaged thereby are reduced,

Fig. 5 is a sectional plan view showing another modification in whichthe sleeve is formed with a flange adapted to be fixed to the propellershaft,

Fig. 6 is an end elevation of Fig. 5,

Fig. 7 is a sectional plan view showing a propeller having three blades,

Fig. 8 is an end View of the propeller shown in Fig. 7, and

Fig. 9 is a sectional plan view of a propeller in which the constructionof the blades and the sleeves carrying the same is the same as thatshown in Figs. 7 and 8, the manner of mounting the said sleeve on thepropeller shaft being different from what has been shown in Figs. '7 and8.

In Figs. 1 to 3 I have shown a propeller which comprises two oppositelyarranged blades 1. The hub of the said propeller comprises a sleevecomprising two integral portions l I and a hub member 9 extendingtransversely through the said sleeves, the said hub member 9 being fixedto the tapering end it of a propeller shaft 8 by means of a cap 52screwed on the screw-threaded end ii of the shaft, the sleeve i, i beingformed at its outer end with a circular cut-out portion [3 for thepassage of the hub member 9 therethrough. The sleeve i, i is formed witha longitudinal slot 2, 2 extending from end to end and including thecircular cut-out portion !3. At the opposite sides of the said slots thewalls of the sleeve are formed with-eyes 3 for the passage of clampingbolts 4 therethrough.

The sleeves l, l have the roots 6, 6 of the blades 1, fitted therein,and they are formed with internal screw-threads engaged by correspondingscrew-threads of the roots 6, 6. The blades are fixed in position bymeans of the said screwthreads and the clamping bolts 4 by means ofwhich the sleeves are held in clamping engagement with the roots, theelasticity of the sleeves being sufficient to permit such clamping. Byhaving the slot 2, 2 extending continuously all through the length ofthe sleeve i, l a uniform pressure is exerted by the sleeve on the rootsall over the length thereof. Therefore the blades are securely fixed inposition within the sleeve.

By thus clamping the sleeve on the roots 6 all over the length thereof Iam enabled to reduce the length of the sleeve i, i as compared to theconstruction shown in Figs. 1 to 3. In Fig. 4 I have shown amodificationin which the length of the sleeve has thus been reduced, andin which a single clamping bolt is provided for each root. Otherwise theconstruction of the hub is the same as has been described with referenceto Figs. 1 to 3; and the same letters of reference have been used toindicate corresponding parts. The roots of the blades and the sleeveswhich are reduced in length have received the reference characters 46and M respectively, and the clamping bolts only one of which is providedfor each blade have received the reference character 44. By providing ablade root of large diameter the construction may be adapted to theforces developed in the hub by the operation of the propeller.

In Figs. 5 and 6 I have shown a modification in which the hub is fixedto the: propeller shaft 8 in a different way. The sleeve 5! in which theroots 5% of the propeller blades are fitted is formed with alongitudinal slot 52 extending all over the length of the sleeve. Thesleeve is formed with internal screw-threads corresponding to thescrew-threaded roots 56 of the blades and two eyes 5-53 and clampingbolts 54 are provided for clamping the sleeve on the roots 56.

At the side opposite to the slot 52 the sleeve 5| is formed with aflange l5 fixed to a flange l4 formed at the end of the propeller shaft8 by means of screws l6.

As appears from the figures the length of the sleeve 5! is furtherreduced as'compared to the length of the sleeve 4! shown in Fig. 4, andyet the strength of the construction is not reduced, because the activelength of the sleeve which is in clamping engagement with the roots 56is not reduced in length. Also in this case the roots of the blades andthe sleeve are formed with corresponding screw-threads.

In Figs. 7 and 8 I have shown a propeller which is provided with threeblades. The construction of the hub is similar in principle to thatshown in Figs. 5 and 6, the propeller shaft 8 being formed with a flangel4 having a flange l5 of the hub fixed thereto by screws I6. Thehub isformed with three integral sleeves H arranged so as to radiate from theaxis of the propeller, and at the outer side of the hub each sleeve isformed with a longitudinal slot 12 extending all over the length of eachsleeve and to a circular cut-out portion l1 thereof. Adjacent the saidslots the sleeves are formed with flanges 13 formed with bores for thepassage of pairs of clamping screws 14 therethrough. The roots of theblades and the sleeve are formed with corresponding screw-threads 16. Itwill be readily understood that the sleeves are pressed into clampingengagement with the whole length of the roots.

In Fig. 9 I have shown a propeller in which the construction of the hubis the same as has been described with reference to Figs. '7 and 8 andthe same numerals of reference have been used to indicate correspondingparts. However, the hub is intended to be fixed to a propeller shaft 8,In which extends through the same, and for this purpose a tubularintermediate member I9 is provided which is formed with a flange l8fixed to the flange I5 of the hub, the said tubular member l9 fitting onthe: tapering end ID of the propeller shaft and being fixed in positionthereon by means of the cap screw l2.

By providing the said intermediate member the hub may be mounted at willeither on a propeller shaft formed with a fiange I4 or on a propellershaft formed with a tapering end In.

I claim: o

1. A propeller, comprising an integral'longitudinally slotted sleeveadapted to be fixed to a propeller shaft, a blade fitted with its rootin said sleeve, and means to clamp said sleeve on said root, the slot ofsaid sleeve extending in the body of the sleeve from the end thereof andbeyond the root of the said blade so far that the sleeve. is insubstantially uniform clamping engagement with the root all over thelength thereof.

2. A propeller, comprising an integral sleeve adapted to be fixed to apropeller shaft and formed with a longitudinal slot extending from endto end over the length of the whole structure, a blade fitted with itsroot in said sleeve, and means to clamp said sleeve on the whole part ofthe root of the blade engaged thereby.

3. A propeller, comprising an integral sleeve adapted to be fixed to apropeller shaft and formed with a longitudinal slot extending over thewhole length thereof, blades fitted with their roots in opposite ends ofsaid sleeve, and means to clamp said sleeve on the whole parts of theroots of the blades engaged thereby.

4. A propeller, comprising a plurality of sleeves made integral andarranged so as to radiate from an axis disposed transversely thereof andeach formed with a longitudinal slot, said slots extending over thewhole length of said sleeves and merging into one another at the innerends of said sleeves across the central portion of the structure, saidsleeves being adapted to be fixed to a propeller shaft, blades fitted insaid sleeves, and means to clamp said sleeves on the whole length of theblades engaged thereby.

5. A propeller as claimed in claim 3, in which the longitudinal slot isprovided at the front side of said sleeve and comprises an enlargedportion at its middle located in axial alignment with the part of thesleeve which is to be fixed to the propeller shaft, and means accessiblethrough said enlarged portion for fixing said sleeve to the propellershaft.

6. A propeller as claimed in claim 3, in which the longitudinal slot isprovided at the front side of said sleeve and comprises an enlargedportion at its middle, and in which the sleeve is formed with a hubmember adapted to be fixed to the propeller shaft and extendingtransversely through the sleeve and towards said enlarged portion.

'7. A propeller as claimed in claim 2, in which the longitudinal slot isprovided at the front side of said sleeve, and in which the said sleeveis constructed at its rear side for being secured to the propellershaft.

MANFRED GRABARSE.

